Setting Object Properties

If you have any questions during development, post them on the Issues page of GitHub. For details about parameters and usage of each API, see the API Reference.

You can set properties for an object when uploading it. Object properties include the object length, MIME type, MD5 value (for verification), storage class, and customized metadata. You can set properties for an object that is being uploaded in streaming, file-based, or multipart mode or when copying the object.

The following table describes object properties.

Property Name	Description	Default Value
Content-Length	Indicates the object length. If the object length exceeds the file length, the object will be truncated.	Actual length of the file
Content-Type	Indicates the MIME type of the object, which defines the type and network code of the object as well as in which mode and coding will the browser read the object.	binary/octet-stream
Content-MD5	Indicates the base64-encoded digest of the object data. It is provided to the OBS server to verify data integrity.	None
Storage class	Indicates the storage class of the object. Different storage classes meet different needs for storage performance and costs. The value defaults to be the same as the object's residing bucket and can be changed.	None
Customized metadata	Indicates the user-defined description of the object. It is used to facilitate the customized management on the object.	None

Setting the Length for an Object

// Create an instance of ObsClient.
var obsClient = new ObsClient({
    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
    // The front-end code does not have the process environment variable, so you need to use a module bundler like webpack to define the process variable.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    access_key_id: process.env.AccessKeyID,
    secret_access_key: process.env.SecretAccessKey,
    // Replace the example endpoint with the actual one in your case.
    server: 'https://obs.eu-west-101.myhuaweicloud.eu'
});

obsClient.putObject({
       Bucket: 'bucketname',
       Key: 'objectname',
       SourceFile: document.getElementById('input-file').files[0],
       ContentLength: 1024 * 1024 // 1MB
}, function (err, result) {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
       }
});

Use the ContentLength parameter to specify the object length.

Setting the MIME Type for an Object

// Create an instance of ObsClient.
var obsClient = new ObsClient({
    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
    // The front-end code does not have the process environment variable, so you need to use a module bundler like webpack to define the process variable.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    access_key_id: process.env.AccessKeyID,
    secret_access_key: process.env.SecretAccessKey,
    // Replace the example endpoint with the actual one in your case.
    server: 'https://obs.eu-west-101.myhuaweicloud.eu'
});

// Upload an image.
obsClient.putObject({
       Bucket: 'bucketname',
       Key: 'objectname.jpg',
       SourceFile: document.getElementById('input-file').files[0],
       ContentType: 'image/jpeg'
}, function (err, result) {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
       }
});

Use the ContentType parameter to set the MIME type for an object.
If this property is not specified, the SDK will automatically identify the MIME type according to the name suffix of the uploaded object. For example, if the suffix of the file is .xml (.html), the object will be identified as an application/xml (text/html) file.

Setting the MD5 Value for an Object

// Create an instance of ObsClient.
var obsClient = new ObsClient({
    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
    // The front-end code does not have the process environment variable, so you need to use a module bundler like webpack to define the process variable.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    access_key_id: process.env.AccessKeyID,
    secret_access_key: process.env.SecretAccessKey,
    // Replace the example endpoint with the actual one in your case.
    server: 'https://obs.eu-west-101.myhuaweicloud.eu'
});

obsClient.putObject({
       Bucket : 'bucketname',
       Key : 'objectname',
       SourceFile : document.getElementById('input-file').files[0],
       ContentMD5 : 'your md5 which should be encoded by base64'
}, function (err, result) {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
       }
});

Use the ContentMD5 parameter to specify the MD5 value for an object.
The MD5 value of an object must be a base64-encoded digest.
The OBS server will compare this MD5 value with the MD5 value obtained by object data calculation. If the two values are not the same, the upload fails with an HTTP 400 error returned.
If the MD5 value is not specified, the OBS server will skip MD5 value verification.

Setting the Storage Class for an Object

// Create an instance of ObsClient.
var obsClient = new ObsClient({
    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
    // The front-end code does not have the process environment variable, so you need to use a module bundler like webpack to define the process variable.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    access_key_id: process.env.AccessKeyID,
    secret_access_key: process.env.SecretAccessKey,
    // Replace the example endpoint with the actual one in your case.
    server: 'https://obs.eu-west-101.myhuaweicloud.eu'
});

obsClient.putObject({
       Bucket : 'bucketname',
       Key : 'objectname',
       SourceFile : document.getElementById('input-file').files[0],
       // Set the storage class to Archive.
       StorageClass : ObsClient.enums.StorageClassCold
}, function (err, result) {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
       }
});

Use the StorageClass parameter to set the storage class for an object.
If you do not set the storage class for an object, the storage class of the object will be the same as that of its residing bucket.
OBS provides objects with three storage classes which are consistent with those provided for buckets.
Before downloading an Archive object, you must restore it.

Customizing Metadata for an Object

// Create an instance of ObsClient.
var obsClient = new ObsClient({
    // Hard-coded or plaintext AK/SK are risky. For security purposes, encrypt your AK/SK and store them in the configuration file or environment variables. In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, configure environment variables AccessKeyID and SecretAccessKey.
    // The front-end code does not have the process environment variable, so you need to use a module bundler like webpack to define the process variable.
    // Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    access_key_id: process.env.AccessKeyID,
    secret_access_key: process.env.SecretAccessKey,
    // Replace the example endpoint with the actual one in your case.
    server: 'https://obs.eu-west-101.myhuaweicloud.eu'
});

obsClient.putObject({
       Bucket : 'bucketname',
       Key : 'objectname',
       SourceFile : document.getElementById('input-file').files[0],
       Metadata : {'property1':'property-value1', 'property2' : 'property-value2'},
}, function (err, result) {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
       }
});

Use the Metadata parameter to specify the customized metadata for an object.
In the preceding code, two pieces of metadata named property1 and property2 are customized and their respective values are set to property-value1 and property-value2.
An object can have multiple pieces of metadata whose total size cannot exceed 8 KB.
The customized object metadata can be obtained by using ObsClient.getObjectMetadata. For details, see Obtaining Object Properties.
When you call ObsClient.getObject to download an object, its customized metadata will also be downloaded.

Parent topic: Object Upload

Previous topic: Creating a Folder

Next topic: Performing a Multipart Upload

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